So, here is my constructed theory based on what I've been collected from Shawols all over my TL

#Dont_Call_Me is the reality of a dystopia destroyed by allegedly bombs and #Atlantis is the post-dystopia utopian world, like the utopia after the disaster.
#SHINee #샤이니

Elaboration:
Atlantis originated from Plato's Timaeus & Critias, which often interpreted as a utopian island, later sank down into the Atlantic Ocean
The origin of the word "utopia" also describes a fictional island in Atlantic Ocean
Utopia can be seen as imaginary perfect world

Atlantis is believed to be destroyed/sank down into the ocean by the Thera eruption (Minoan eruption)

In one of Jinki's teaser, there is a photo of an erupting volcano.

The impact of Atlantis, a utopia, being destroyed may have led to the resulting of a dystopia, more specifically, a post apocalyptic world.
The way SHINee dresses and the characters teasers depict disasters are usually elements seen in apocalyptic/post-apocalyptic movies.

In (post) apocalyptic movies, the apocalypse usually resulted from nuclear bombs and *cough* alien invasions.
There is one theory that Atlantis was destroyed by bombs and B28 is a type of nuclear bomb and interestingly was carried by a certain US *Navy* attack aircraft

Interestingly, in the fake reality teasers, we can see a scenario of a peaceful world but there is also a hint of disaster here and there like the smoke coming from Minho's car resembling the industrial exhaust or the fire that blazes here and there

Notice how the elevator go UP instead of going DOWN like in Taemin's shot, and the outfit they use to perform the song ended up in a background of "sky" and "above water" => The Atlanteans has arisen.
Rising also serves as symbolism of a dystopia rising up to be a utopia again.

Also the setting for Atlantis teaser pic really describes an "unreal" world: boat in tree, door without any room, and looks abandoned, like a ruined yet still beautiful. Exactly how people would imagine Atlantis be like in term of adjectives.

The phone used in DCM is black, the one in Atlantis is white, and the one in Fake Reality is red. Black = Dystopia, White = Utopia, Red = Dangered Zone.
Also the phone in DCM submerged into the water mean no capability to call => no means of contact => isolation

SHINee are sea people.
The sea creatures items, sea accessories, that one 3 seahorses poster looks like Olympic poster and the missing fish flyer kinda eluded to the fact that this is in fact a under sea civilization, and in a more real sense, fish, squids and creatures alike.

Also remember Kibum fishing in an empty bowl and Taemin carried a suitcase of 4 fish in fake reality => the fish in empty bowl represents an unreal & trapped situation and the fish in Taemin's suitcase resembles SHINee, suffered in apocalyptic world because they're out of water

Also as established, Atlantis was destroyed in resumedly either an eruption or a nuclear bomb explosion. DCM reality leans more towards the nuclear bomb scenario, we can see how it polluted the water, create poison gas & acid rain. Save water save us = save SHINee the sea people

In conclusion: SHINee is the people of Atlantis, which suffered a disaster and become a dystopia, submerged into the sea and people sea people, trying to rise above the water to make Atlantis a utopia again.

Also side note yeah I noticed that the B28 is a code for Atlantis the shipwreck in Late Erie and guess what SHINee's main icon for this comeback is? A ship.

Also because Atlantis was originated from Plato, guess who's responsible for Plato related stuff